With the increasing usage of reinforced plastics in automotive appearance panels and support structures, the use of polymeric based thermoset adhesives to assemble these components together is also increasing. One major difference exists between the technique of assembling automotive components together by mechanical means and that of the adhesive means. A thermoset adhesive which is generally used for its structural strength requires a relatively long period of time to cure in order to reach its bond strength. A common practice used in the automotive industry in curing a polymeric based thermoset adhesive is to cure by exposure to forced hot air. The time required to cure an adhesive assembled automotive assembly by forced hot air can be extensive, i.e., in the order of 10 to 20 minutes or longer.
The long cure time required for adhesive assembled automotive parts presents a hindrance to the further development of such applications. Prolonged cure time results in the necessity of having large cure ovens and large storage facilities which are not permitted in a mass production process. Others have proposed methods for curing thermoset adhesives by subjecting them to radiations such as microwave or dielectric power. However, these techniques normally require chemical modification of the adhesive such that the end groups on the molecules are able to participate in crosslinking reactions. Furthermore, even with the conventional microwave heating technique, the time required for curing is still in the order of minutes.
It is therefore a general object of the present invention to provide a method of rapid curing a polymeric based thermoset adhesive so that it is compatible with a mass production process.
It is another object of the present invention to provide a method of rapid curing a polymeric based thermoset adhesive at low cost.